IOS：用你的手指画一条线

我想知道用白色的手指画一条线的方法是什么。 我想做一个画板，我想开始理解如何绘制一个简单的线条或用手指完成的轨迹。 我该怎么做？

Answer 1

我已经了解你的问题。 请看下面的代码，它会全部用于你。

-(void)intializeDrawImage { drawImage = [[UIImageView alloc]initWithFrame:CGRectMake(0, 100, 320, 320)]; [drawImage setBackgroundColor:[UIColor purpleColor]]; [drawImage setUserInteractionEnabled:YES]; [self.view addSubview:drawImage]; } - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { NSLog(@"touchesBegan"); UITouch *touch = [touches anyObject]; CGPoint p = [touch locationInView:drawImage]; startPoint = p; } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { NSLog(@"touchesMoved"); UITouch *touch = [touches anyObject]; CGPoint p = [touch locationInView:drawImage]; [self drawLineFrom:startPoint endPoint:p]; } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { [self touchesMoved:touches withEvent:event]; } - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { [self touchesEnded:touches withEvent:event]; } -(void)drawLineFrom:(CGPoint)from endPoint:(CGPoint)to { drawImage.image = [UIImage imageNamed:@""]; UIGraphicsBeginImageContext(drawImage.frame.size); [drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width, drawImage.frame.size.height)]; [[UIColor greenColor] set]; CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0f); CGContextMoveToPoint(UIGraphicsGetCurrentContext(), from.x, from.y); CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), to.x , to.y); CGContextStrokePath(UIGraphicsGetCurrentContext()); drawImage.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); }